It's a really odd social phenomenon. It's one thing to say "We don't like X and find it in poor taste. Please don't do that"
I don't like it when folks say such things, but I understand it. Instead, what many folks seem to be saying is that based on one thing they can tell what the person is like inside. It's an amazingly-broad generalization and people seem to be enormously confident of themselves when they make it. I can look at your shoe or color of your shirt and conclude that you are a bad person inside.
I don't find that to be especially rational, but what is one to do?